A physics-based earthquake simulator and its application to seismic hazard assessment in Calabria (Southern Italy) region     

Rodolfo Console  Anna Nardi  Roberto Carluccio  Maura Murru  Giuseppe Falcone  Tom Parsons 《Acta Geophysica》2017,65(1):243-257

The use of a newly developed earthquake simulator has allowed the production of catalogs lasting 100 kyr and containing more than 100,000 events of magnitudes ≥4.5. The model of the fault system upon which we applied the simulator code was obtained from the DISS 3.2.0 database, selecting all the faults that are recognized on the Calabria region, for a total of 22 fault segments. The application of our simulation algorithm provides typical features in time, space and magnitude behavior of the seismicity, which can be compared with those of the real observations. The results of the physics-based simulator algorithm were compared with those obtained by an alternative method using a slip-rate balanced technique. Finally, as an example of a possible use of synthetic catalogs, an attenuation law has been applied to all the events reported in the synthetic catalog for the production of maps showing the exceedance probability of given values of PGA on the territory under investigation.  相似文献   

Geoprospecting Survey in the Archaeological Site of <Emphasis Type="Italic">Aquinum</Emphasis> (Lazio,Central Italy)     

Maurizio Lazzari  Lara De Giorgi  Giuseppe Ceraudo  Raffaele Persico 《Surveys in Geophysics》2018,39(6):1167-1180

In this paper, the results of a ground penetrating radar (GPR) prospecting survey performed in the Roman archaeological site of Aquinum are shown. The prospecting was performed in two distinct areas. The first one was close to the remains of the ancient thermal baths, where a public project intends to build a car park. The second area is close to an apsidal Roman building, and it was of interest to establish whether, and possibly up to what extent, the remains of this partially revealed structure continue, or maybe whether meaningful further structures are present.  相似文献   

Developing collapse fragility curves for base-isolated buildings     

Donatello Cardone  Giuseppe Perrone  Valentino Piesco 《地震工程与结构动力学》2019,48(1):78-102

Seismic isolation technique is increasingly used both for the design of new buildings and for the seismic retrofit of existing buildings. Nevertheless, so far, little attention has been paid on the collapse capacity of these structures, mainly because it requires refined nonlinear models and careful consideration of different sources of uncertainties. To fill this gap, a set of collapse fragility functions for existing reinforced concrete-frame buildings, designed for gravity loads only and then retrofitted with different isolation systems (including rubber-based and friction-based isolation systems), are derived in this study. For completeness, buildings with low and high seismic resistance are also considered. Collapse fragility functions are derived through incremental dynamic analysis, considering different collapse conditions both for isolation system and superstructure. For each case study building, mean and dispersion values are obtained considering both aleatory and epistemic uncertainties, due to record-to record and model variability, respectively. Finally, some comments on the possible use of the results of this study for practical applications are made.  相似文献   

Human‐induced hazardous debris flows in Carrara marble basins (Tuscany,Italy)     

Carlo Baroni  Giuseppe Bruschi  Adriano Ribolini 《地球表面变化过程与地形》2000,25(1):93-103

In Carrara marble basins, the long and intensive quarrying activities (which began in the first century BC ) have produced extensive dump deposits, locally known as ravaneti. Ravaneti are of such large dimensions and diffusion as to make them a widespread landform of the Apuane Alps (Tuscany). In recent years these quarry dump deposits have been affected by frequent debris flows, more than 50 in 1996/97. This phenomenon is the most significant currently active geomorphological process in this landscape. The evolution of quarrying techniques produced a variety of sedimentological compositions of ravaneti. The debris flows analysed involve only the surface layers where debris is mixed with fine material with a lower permeability (active ravaneti) than the coarser underlying debris (older ravaneti). The presence of different permeability layers causes a wetting front to move downwards. Source area observations indicate a soil slip movement in the initial phases of the failure. The transformation of landslides into debris flow occurs by means of both soil contractive failure and an increase of granular temperature. The morphological and sedimentological analyses of depositional lobes resulted in a classification of three types of lobe, based on fabric–morphometry relationships allowing the identification of different flow dynamics: (1) type A lobe (platy form), matrix‐supported and well developed fabric with general tendency of ab clast plane strikes to lie generally parallel to flow direction as a consequence of laminar flow; (2) type B lobe (elongated form), clast‐supported and random fabric as a consequence of both turbulent flow and coarser composition of starting material; (3) type C lobe, intermediate type A–B morphometry, tendency for ab clast plane to lie in a semi‐circle around the main flow direction determined by the presence of secondary flow lines divergent from it in the stopping phase. In Carrara marble basins, the anomalous frequency with which debris flows tend to be triggered by medium‐intensity rainstorms (about 30 mm h⁻¹ rainfall) is due to the recent increases in silt dump produced by modern quarrying techniques. This represents a significant example of debris flows as an environmental problem in major anthromorphized landscapes. Copyright © 2000 John Wiley & Sons, Ltd.  相似文献   

Seismic markers of the Messinian salinity crisis in the deep Ionian Basin     

Angelo Camerlenghi  Anna Del Ben  Christian Hübscher  Edy Forlin  Riccardo Geletti  Giuseppe Brancatelli  Aaron Micallef  Marco Saule  Lorenzo Facchin 《Basin Research》2020,32(4):716-738

We conduct the seismic signal analysis on vintage and recently collected multichannel seismic reflection profiles from the Ionian Basin to characterize the deep basin Messinian evaporites. These evaporites were deposited in deep and marginal Mediterranean sedimentary basins as a consequence of the “salinity crisis” between 5.97 and 5.33 Ma, a basin-wide oceanographic and ecological crisis whose origin remains poorly understood. The seismic markers of the Messinian evaporites in the deep Mediterranean basins can be divided in two end-members, one of which is the typical “trilogy” of gypsum and clastics (Lower Unit – LU), halite (Mobile Unit – MU) and upper anhydrite and marl layers (Upper Unit – UU) traced in the Western Mediterranean Basins. The other end-member is a single MU unit subdivided in seven sub-units by clastic interlayers located in the Levant Basin. The causes of these different seismic expressions of the Messinian salinity crisis (MSC) appear to be related to a morphological separation between the two basins by the structural regional sill of the Sicily Channel. With the aid of velocity analyses and seismic imaging via prestack migration in time and depth domains, we define for the first time the seismic signature of the Messinian evaporites in the deep Ionian Basin, which differs from the known end-members. In addition, we identify different evaporitic depositional settings suggesting a laterally discontinuous deposition. With the information gathered we quantify the volume of evaporitic deposits in the deep Ionian Basin as 500,000 km³ ± 10%. This figure allows us to speculate that the total volume of salts in the Mediterranean basin is larger than commonly assumed. Different depositional units in the Ionian Basin suggest that during the MSC it was separated from the Western Mediterranean by physical thresholds, from the Po Plain/Northern Adriatic Basin, and the Levant Basin, likely reflecting different hydrological and climatic conditions. Finally, the evidence of erosional surfaces and V-shaped valleys at the top of the MSC unit, together with sharp evaporites pinch out on evaporite-free pre-Messinian structural highs, suggest an extreme Messinian Stage 3 base level draw down in the Ionian Basin. Such evidence should be carefully evaluated in the light of Messinian and post-Messinian vertical crustal movements in the area. The results of this study demonstrates the importance of extracting from seismic data the Messinian paleotopography, the paleomorphology and the detailed stratal architecture in the in order to advance in the understanding of the deep basins Messinian depositional environments.  相似文献   

Contribution to knowledge regarding the sources of earthquakes on the island of Ischia (Southern Italy)     

Cubellis  Elena  Luongo  Giuseppe  Obrizzo  Francesco  Sepe  Vincenzo  Tammaro  Umberto 《Natural Hazards》2020,100(3):955-994

Natural Hazards - This paper analyses data regarding the seismicity and ground deformations of the island of Ischia. The goal is to describe these phenomena as a space–time process, exploring...  相似文献   

Tidal effects on the LAGEOS–LARES satellites and the LARASE program     

Giuseppe Pucacco  David M. Lucchesi 《Celestial Mechanics and Dynamical Astronomy》2018,130(10):66

The effects of solid and ocean tides have been computed on the right ascension of the ascending node of the two LAGEOS and LARES satellites and on the argument of pericenter of LAGEOS II. Their effects—together with the possible mis-modeling related to systematic errors in the estimate of the tidal coefficients, especially in the case of ocean tides—are quite important to be well established for the key role of the LAGEOS satellites, as well as of the newly LARES, in space geodesy and geophysics as well as in fundamental physics measurements. In the case of the measurement of the Lense–Thirring effect, the mis-modeling of long-period tides may mimic a secular effect on the cited orbital elements, thus producing a degradation in the measurement of the relativistic precession. A suitable combination of the orbital elements of the three satellites can help in avoiding the effects of the long-period tides of degree \(\ell =2\) (as for the Lunar solid tides with periods of 18.6 and 9.3 years) and \(\ell =4\), but other long-period tides, as the ocean \(K_1\) tide, which has the same periodicities of the right ascension of the ascending node \(\varOmega \) of the satellites, may strongly influence the measurement, especially if it is performed over a relatively short time span. These results are particularly important in the case of LARES, since they are new and because of the role that the orbit of LARES, and especially of its ascending node right ascension, will have in a new measurement of the Lense–Thirring effect by the joint analysis of its orbit with that of the two LAGEOS.  相似文献   

The dynamics of the de Sitter resonance     

Alessandra Celletti  Fabrizio Paita  Giuseppe Pucacco 《Celestial Mechanics and Dynamical Astronomy》2018,130(2):15

We study the dynamics of the de Sitter resonance, namely the stable equilibrium configuration of the first three Galilean satellites. We clarify the relation between this family of configurations and the more general Laplace resonant states. In order to describe the dynamics around the de Sitter stable equilibrium, a one-degree-of-freedom Hamiltonian normal form is constructed and exploited to identify initial conditions leading to the two families. The normal form Hamiltonian is used to check the accuracy in the location of the equilibrium positions. Besides, it gives a measure of how sensitive it is with respect to the different perturbations acting on the system. By looking at the phase plane of the normal form, we can identify a Laplace-like configuration, which highlights many substantial aspects of the observed one.  相似文献   

Responses of a Northern Adriatic Ampelisca-Corbula community to seasonality and short-term hydrological changes in the Po river     

N'siala GM  Grandi V  Iotti M  Montanari G  Prevedelli D  Simonini R 《Marine environmental research》2008,66(4):466-476

During the 20th century, increased nutrient inflow has increased the frequency and intensity of eutrophication events in the North-western Adriatic Sea. More recently, evidence of a reduction in the Po river flow and a recovery of the benthic environment were reported. We examined the role played by Po river regime and seasonality in determining the temporal pattern of macrozoobenthos variation: samples were collected from a site located 10-12km off Cesenatico during two years from October 2004 to September 2006, when the mean Po discharge remained exceptionally low. 88 taxa were found, and the community was dominated by few species: Ampelisca diadema, Lumbrineris latreillii, Corbula gibba, Aricidea claudiae, Levinsenia gracilis and Nucula nucleus account for about 80% of total abundances. The density of these species exhibited a marked seasonal variability. Moreover, the total abundance and the density of the sensitive species, A. diadema, were negatively affected by several disturbance events (hypoxic conditions, frequent storms and an anomalous winter flood) that occurred between November 2005 and March 2006. The reduction of C. gibba and the increase of A. diadema densities observed in the investigated period, and verified recently by other authors could be related to the reduction in river inputs as a consequence of climatic changes.  相似文献   

Assessing the ecological status of the North-western Adriatic Sea within the European Water Framework Directive: a comparison of Bentix, AMBI and M-AMBI methods     

Roberto Simonini  Valentina Grandi  Gloria Massamba-N'Siala  Mirko Iotti  Giuseppe Montanari  & Daniela Prevedelli 《Marine Ecology》2009,30(2):241-254

In this paper we looked for the most suitable method for benthic ecological quality status (EcoQS) assessment of the North-western Adriatic Sea. Taking into account the historical and present information, we inter-compared our expectations in terms of EcoQS, with the Bentix, AMBI and M-AMBI classification metrics results, and investigated the sensitivity of these indices to the spatial, seasonal and inter-annual variability of benthic communities. The sampling sites were located at increasing distances with respect to the Po River mouth, along an (inverse) gradient of eutrophication. Moreover, a 2-year monthly monitoring plan (October 2004–September 2006) was carried out at the CEBEB site, located in a central position with respect to the investigated area. The results highlighted that the three indices differed in the sensitivity to spatial and temporal variability of the benthic communities. The strong seasonal and inter-annual changes in the benthic communities had a significant effect on the Bentix, whereas no relevant modifications were observed on the EcoQS assignation obtained using the M-AMBI and AMBI methods. The environmental quality ratios (EQR) values and EcoQS classification obtained by the Bentix and AMBI did not match expectations, as they were not inversely correlated with the site distances with respect to the Po mouth, whereas the M-AMBI clearly discriminated the most and the least eutrophicated sites. It thus appears that the M-AMBI could be considered to be the most valuable method for the ecological-status assessment of the North-western Adriatic Sea benthic ecosystem.  相似文献